Sprinkler base



FIG. 1 is a top perspective view of a sprinkler base according to the invention;

FIG. 2 is a bottom plan view of the article shown in FIG. 1;

FIG. 3 is a top plan view of the article of FIG. 1; and,

FIG. 4 is a side view of the article shown in FIG. 1. 

The ornamental design for a sprinkler base, as shown and described. 